John Curl's Blowtorch preamplifier part II - Page 3211 - diyAudio
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Old 1st January 2013, 10:09 PM   #32101
fas42 is offline fas42  Australia
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Very simple: neutralise the love of money ...

Frank
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Old 1st January 2013, 10:29 PM   #32102
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Very simple: neutralise the love of money ...

Frank
Indeed. I did it with myself, though the majority of others don't follow…
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Old 1st January 2013, 10:49 PM   #32103
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Here is a picture of the current into the half bridge feeding a small power supply. The transformer is rated 16 Volt CT at .8A and the filter is 10,000 uf and .1 uF, the load is 50 ohms. The image is 16 averages.

So what is so interesting?
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Old 1st January 2013, 10:55 PM   #32104
bcarso is offline bcarso  United States
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Originally Posted by simon7000 View Post
Here is a picture of the current into the half bridge feeding a small power supply. The transformer is rated 16 Volt CT at .8A and the filter is 10,000 uf and .1 uF, the load is 50 ohms. The image is 16 averages.

So what is so interesting?
Unless a transformer has a bifilar-wound secondary to achieve the center tapped operation, the two halves of the winding will have different resistances, if wound one on top of the other for the same number of turns and hence open-circuit voltages. This leads to a lot of fundamental coming through when you draw current.
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Old 1st January 2013, 11:01 PM   #32105
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Unless a transformer has a bifilar-wound secondary to achieve the center tapped operation, the two halves of the winding will have different resistances, if wound one on top of the other for the same number of turns and hence open-circuit voltages. This leads to a lot of fundamental coming through when you draw current.
And what are the other solutions? BTY this is from a Signal dual primary dual secondary flat-pack!
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Old 1st January 2013, 11:11 PM   #32106
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but our sales and reviewer rating
How many Blowtorch were sell ?
Can-you compare your sells with the ones of Marantz, Sony, Philips, Denon, Nad, Pioneer, Rotel, Yamaha etc. ?
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Although totally unimportant to anyone here, I find no rational in that route.
Happy new-year George (This is Totally no rational).
I agree with you most of the time, and specially on this way :-)
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Old 1st January 2013, 11:37 PM   #32107
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Many talk of the "evilness" of MP3 ... or is it? I took the right channel of that 2L recording of the Britten work, 96kHz, and gave it it the MP3 treatment ... gasp, horror of horrors, it must be totally ruined!! Let's see then: to make it fair I used Lame and forced it to use high quality options, a bit rate of 320kbps. But still, the 52Meg file was clobbered, to output a file just over 7Meg. Heavens, the track must be completely ruined ...!!

Okay, suck the 96k file into Audacity, and the generated MP3, synchronise, invert one and mix, and what does the difference file look like? Like this:

2L50SACD_tr1_DXD_stereo_2012-12-29_14-09-58-07.jpg

Hmmm, mostly down at least 60dB, not too terrible; but there are a couple of nasty looking spikes, what's in them? Lets zoom in on one:

2L50SACD_tr1_DXD_stereo_2012-12-29_14-09-58-08.jpg

Well, this looks to be pretty high frequency stuff, I don't think it's going to be audible. But let's look at the spectrum of just that zoomed in bit, what does it show?

2L50SACD_tr1_DXD_stereo_2012-12-29_14-09-58-09.jpg

Oh dear, mostly very high frequency material - you have to wonder how relevant it's going to be ...

So, this dreadful MP3 business didn't do so horribly after all in processing this "audiophile" recording, so why does it sound so terrible, I wonder ...?

Frank

Last edited by fas42; 1st January 2013 at 11:44 PM.
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Old 2nd January 2013, 12:01 AM   #32108
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So, this dreadful MP3 business didn't do so horribly after all in processing this "audiophile" recording, so why does it sound so terrible, I wonder ...?
Who pretend MP3 sound "terrible" apart JC and some maniacs audiophiles who love the sound of 40 years old analog tapes ?
(Happy new year, fas42, I love your clever way to explore the things).
It do the same job than Mini cassette, hundred time better: provide a light access to music. As far i'm concerned, i just avoid-it like hell from any professional use.
There is no more problem about-it, nowadays, hard disks, USB Keys and flash memory sticks are cheap enough for we do not need-it any more, apart for live web diffusion.
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Old 2nd January 2013, 12:24 AM   #32109
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What I would really like to know is what did not work in the experimentation leading toward imperceptible compression algorithms. That would highlight the real aspects we should look to in audio overall. Further applying that knowledge to speakers could be really useful. We know its very difficult to reproduce a "waveform" acoustically. Perhaps the basic concept is flawed and a different approach to creating pressure waves that would better mimic what we hear exists.

And there is the hazard of conflating accuracy and "good sound". Floyd Toole pretty conclusively proved that they are not synonymous, with audiences preferring a rolled off top. Good sound has no bounds or clear target. In fact it could be argued that it can be influenced by aspects that have zero affect on sound. However customers buy "good sound" and like to be told its more accurate.
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Old 2nd January 2013, 12:31 AM   #32110
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So, this dreadful MP3 business didn't do so horribly after all in processing this "audiophile" recording, so why does it sound so terrible, I wonder ...?
I rather suspect those who say mp3 sounds terrible are listening through a far more terrible DAC For me its not a slam dunk to tell the difference between VBR (or 320k) mp3 and the original redbook. Some loss of ambience perhaps, but not very obvious.

@Demian - did Floyd give details of the electronics he was using when his audiences preferred the HF rolled off? My guess - he had an S-D DAC
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